Thread-cutting device for buttonhole-sewing machines.



R. MUNDLOS.

THREAD CUTTING DEVICE FOR BUTTONHOLE SEWING MACHINE-S.

Patented Mar. 6, 1917.

2 SHEE-SHEET I.

APPLICATION FILED MAY 20, 19,15.

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R. MUNDLOS.

THREAD CUTTING DEVICE FOR BUTTONHOLE SEWING MACHINES.

APPLICATION FILED MAY 20, i915.

' Patented Mar. 6, 1917.

2 SHEETS-SHEET 2.

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mr nan/us zinns uo.. www umu wnnmmau. n cv RICHARD MUEDLos, orMAGEEBURG, GERMANY, Assrenon To THEELRM or H. MUNDLos a oo., 0EMAGDEBURG, GERMANY.

THREAD-CUTTING DEvIoEV Een BUrronnoLE-snwnve' ivraonINEs.

Specification of Lettersilatent.

Patent-canal. c, i917.

Application filed May 20, 1915. vSerial No. 29,290.

Thread-Cutting Devices for Buttonhole- Sewing Machines, of which thefollowing is a specification. l

My invention relates to a thread cutting device or mechanism for sewingmachines and particularly of a kind adapted for use in button holesewing machines.

The object of my invention is to provide a thread cutting mechanism bywhichrthe two threads in the machine, that is the upper thread and thelower thread, Vare simultaneously cut when the machine is at rest.

My invention is shown in the accompanying drawings wherein:

Figure 1 is a side view of the parts of a button hole sewing machineembodying the invention.

Fig. 2 is a plan of the same.

Fig. 3 is a partly sectional view of a part of the mechanism forcutting` the upper thread and the lower thread on alarger scale showingthe parts in the position during the from the sewing plate 12 orthe workcutting operation.

Fig. 4 is a view ofthe mechanism for cutting the lower thread on alarger scale.

The devices for cutting l voff the upper thread and the lower thread orthe upper cutting device and the lower cutting device are held. inoperative interdependence by the presser member so that the two devicessimultaneously begin the cutting operation. The presser member is formedat itsvforeend soas to act like the so-called presserfoot and carries atthis end the detachable blade or cutter 2 for cutting the upper thread.Said cutter 2 is of angular shape and can be easily detached from itscarrier, e. g. for grinding purposes, and again attached thereto withoutthe necessity of removing any other partsfrom their operative positions.The presser member comprises two levers or parts 1a and 1b mounted onhinges 3 and 4 respectively, the partlb being free to turn on its hinge4 to a certain extent independently of the part 1a, the two parts beingturned together about the hinge 8 for the purpose of lifting the presserfoot (fabric or. the like) thereon. rhis turning or oscillating movementof the presser member is effected by means of atreadle (not shown) and amember (not shown) vsuch as a rod or chain connectingv thetreadle withthe vpart 1" as is well understood-by those skilledin the art.` lnactuating the treadle the part 1b is first turned downward alone about4, thereby acting upon an angle y shaped .plate adjustably mounted Von aslotted lever 5 having its fulcrum at 7 and being directly connectedwith the actuating Y rod 8 of the lower cutting device which iscontrolled by a spring. 1'1, by means of a pin 10 engaging the slot 9 ofthe lever 5. The said rod 8 is atvthe other end, connected with the arm1421 of a lever 14 having its fulcrum at 13 below the sewing plate 12and engaging, with its forked arm 141?, the pin loflthe leverlil-operating the blade or cutter 15 for cutting the lower thread. Thecutter 16 is connected with the arm 17 of the lever 19 having itsfulcrum at 15. The

lever arm 17. serves the special .purpose of vpulling oi'lthe lowerthread and the lever 14 is controlled by aspring 20. By the action ofthe part 1b ofthe presser Ymember on theplate 6 of the slotted lever 5the latter is turnedV aboutits fulcrum 7 so that the rod Y 8 engaging.thefslot 9 of the lever 5 by means of its-pin 410, .is longitudinallymoved forward against the action of its spring 11 and thereby the lever14, the cutter 16 and the thread pulling arm 17 are simultaneouslyactuated. 1n turning the lever 5 downward from its normal position theplate 6 acts upon a lever 22 fulcrumed at 21 and controlled by aspring23, so that the lever 22 rotates against the actiony of its spring 23whichholds the lever 22 at all times in conf tact with the plate 6 andalsocauses the lever 22 to return to its normal position when the lever5 reassumes its normal position. In starting the sewing machine thepresser member moves forward, as usually infmachines of this kind, sothat the lever 22 at the ytime will not be in contact with the rod 2,4,engaging only the adjustable plate 6 of the lever 5. At the backwardmovement of the presser member the said rod bearsiagainst theVfore-armof the lever- 22 and is held underpressure by the action of its spring26; thus the rod 24 is moved forward with relation to the presser memberVby the arm or-lever 27, so as to pass by the blade or cutter 2 for theupper thread and cause the latter to be cut on".

lThe angular end 25 of the lever 22 forms a separate part and can beadjusted with relation to the lever by means of a screw and nut 3l in alongitudinal slot 30 of the lever 25. In order to not actuate thecutting off before the machine is stopped a cam lever 33 is connectedwith the disengaging member 32 of the machine drive, said lever 33assuming, as long as the machine is working, a position below theangular plate 6 of the lever 5 so as to lock the latter and the pressermember la lb and thus prevent the cutting devices for the upper and thelower thread from operating. The cam lever 33 is so shaped or fashionedas to be adapted to prevent the machine from being engaged or coupledand started so long as the presser member la all is open or lifted andat the same time to assist in the lifting of the slotted lever V5. Thesaid cam lever 33 has its fulcrum at 34 and is connected with thedisengaging member 32 of the machine by the arm 35 andthe Vlink 3G,lever 37 and link 38. The lever 37 is fulerumed at 39.V As soon as themachine is stopped by means of the disengaging mechanism, the cam lever33 releases the lever 5 and the angular piece 6 attached thereto so thatthe presser member la lb is free to turn or oscillate and the threadcutting devices can be actuated simultaneously by the movement of theslotted lever 5, 6 and the locking lever 22 in the manneraforedescribed.

As soon as the part lb of the presser member is actuated to operate thelevers 5 and 22 and has finished part of its way a pin 40 adjustablymounted at the lower face of the said part lb begins to act on the backend of the part la of the presser member to turn said part lfL about itspivot 3 so that the foreend of the part la is lifted from the machineplate or the fabric thereon. 0n releasing the treadle and the part lbconnected therewith the presser member is returned to its initial ornormal position by means of springs 4l and 42, the former being mountedbetween the superposed ends of the two Y parts lEL lb of the pressermember, the latter acting on the fore-'end of the part la. At the sametime the cam lever 5 is returned to its initial position by means of alink or chain 43 connecting said lever with the part lb of the pressermember.

The rod 24 is moved forward owing to the backward movement of thepresser member whereby the thread pulling member 29 rotatably mount-edon the vertical rod 28, is turned by the lever 27 into the properoperating position. The thread pulling member 29 is provided on itsupper face with ribs or teeth which act to hold the thread and draw sameback again-so that the thread never can be caught.

As regards the operation of the cutter 16 it is to be noted, that thelower thread comes from the bobbinl in 'the bobbincase or boX and passesthrough the vertical hole in the stitching-plate to the work. As thecutting device is being operated the Ylever arm 17 pulls off the threadfrom the bobbin, but said lever arm 27 never can pull the thread out ofthe range of movement of the cutter lf3, since the thread passes throughthe hole in the stitching plate and the cutter moves close by said hole.

What l' claim is:

l. ln a button-hole sewing machine, a presser member fulcrumed to themachineplate, a device for cutting off the upper thread, a device forcutting olf the lower thread, a rod, 24, adapted to actuate the former,and a rod, 8, adapted to actuate the latter, a lever, 5, in operativeconnection with the said rod, 8, and in engagement with the pressermember, and a lever, 22, in engagement with the other rod, 24, and withthev other lever, 5, to be moved simultaneously therewith.

2. In a button-hole sewing machine, a presser member fulcrumed to themachineplate, a device for cutting ofi1 the upper thread, a device forcutting oifthe lower thread, a rod, 24, adapted to aetuate'the formerand a rod, 8, adapted to actuate the latf:

ter, a lever, 5, in operative connection with the said rod, 8, and inengagement with the presser member, a lever 22 in engagement with therod, 24, and the lever, 5, and an adjustable angular end piece, V25, onsaid lever, 22, adapted to bear against the cutter actuating rod, 24.

3, In a button-hole sewing machine, a presser member fulcrumed to themachineplate, a device for cutting Voff the upper thread, a device forcutting oli' the lower thread, a rod, 24, adapted to actuate the formerand a rod, 8, adapted to actuate the latter, a lever, 5, inoperativeconnection with the said rod, 8, and in engagement with the pressermember, a lever, 22, a cam lever, 33, a member, 32, for disengaging themachine drive, and intermediate means con- `necting said cam lever withthe said member, 32, all the parts constructed and arranged so that theaforesaid levers, 5 and 22, are locked when the machine drive isengaged. Y

4. In a. button-hole sewing machine, a

presser member fulcrumed to the machineplate, a device for cutting offthe upper thread, a device for cutting off the lower thread, a rod, 24,adapted to actuate 'the former and a rod, 8, adapted to actuate thelatter, a lever, 5, in operative connection with the said rod, 8, and inengagement withV the presser member, a lever, 22, a cam lever, 33, soshaped or profiled as to prevent`the machine from being engaged orcoupled to start when the presser member is lifted or open, and toassist in lifting the lever 5, a member 32, for disengaging the machinedrive, and intermediate means connecting said cam lever with the saidmember 32.

5. In a button-hole sewing machine, a presser member fulcrumed to themachine plate, a device for cutting off the upper thread, a device forcutting off the lower thread, a rod, 24, adapted to actuate the former,and a rod, 8, adapted to actuate the latter, a lever, 5, in operative'connection with the said rod, 8, and in engagement with the presserinember comprising two superposed parts or levers, the one, la, beingfulcrumed to the machine plate, the other, 1b, being fulcrumed on theformer, so as to act, when actuated, irst on the said lever, 5, alone,and thereafter on the part, 1a, for the purpose of operating same.

6. In a button-hole sewing machine, a presser member fulcrumed to themachine plate, a device for cutting off the upper thread, a device forcutting off the lower thread, a rod, 24, adapted to actuate the former,and a rod, 8, adapted to actuate the latter, a lever, 5, in operativeconnection with the said rod, 8, and in engagement with the pressermember comprising two superposed parts or levers, la, 1b, and twosprings 42, 41, acting on said levers same from being retained, a rod,24, adapted to actuate both the said cutter and the said member, 29, adevice for cutting oftl the lower thread, a rod, 8, adapted to actuatethe latter, a lever, 5, in operative connection with the said rod, 8,and in engagement with the presser member, and av lever, 22, inengagement with the other rod, 24, and with the other lever, 5, to bemoved simultaneously therewith.

8. In a butt-on-hole sewing machine, a presser member fulcrumed to themachineplate, a device for cutting off the upper thread, an actuatingrod, 24, a blade or cutter, 16, for cutting o the lower thread, a threadpulling member, 17, both the latter andthe said cutterl being connectedto rotate about the same pivot 15, an actuating rod, 8, a lever, 5, inoperative connection with the said rod, 8, and in engagement with thepresser member, and a lever, 22, in engagement with the other rod, 24,and with the other lever, 5, to be moved simultaneously therewith.

' In testimony whereof I have afiXed my signature in presence oftwowitnesses.

L. OCHLMANN, A. REILLY.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

